linux-kernel - Re: [RFC DRAFT PATCH] per-buffered-write stream IDs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAF1ivSYLA9=mO_cEQVCuMpEYHHDfZ7p7auKYPmLYGfxgK=SZDg@mail.gmail.com>
Date:	Tue, 21 Apr 2015 11:34:41 -0700
From:	Ming Lin <minggr@...il.com>
To:	Jens Axboe <axboe@...com>
Cc:	Ming Lin <ming.l@...sung.com>, lkml <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, Dave Chinner <david@...morbit.com>,
	Changho Choi-SSI <changho.c@....samsung.com>,
	"Kwan (Hingkwan) Huen-SSI" <kwan.huen@....samsung.com>
Subject: Re: [RFC DRAFT PATCH] per-buffered-write stream IDs

On Tue, Apr 21, 2015 at 10:12 AM, Jens Axboe <axboe@...com> wrote:
> On 04/21/2015 11:09 AM, Ming Lin wrote:
>>
>> Hi Jens,
>>
>> This RFC DRAFT patch is on top of your "[PATCH v2] Support for write
>> stream IDs"
>> I throw it out early to get comments if it's the way to go.
>>
>> Quote LWN(http://lwn.net/Articles/638722):
>>
>> "There would be clear value in a closer association between stream IDs
>> and specific buffered-write operations. Getting there would require
>> storing
>> the stream ID with each dirtied page, though; that, in turn, almost
>> certainly
>> implies shoehorning the stream ID into the associated page structure.
>> That would not be an easy task; it is not surprising that it is not a part
>> of
>> this patch set. Should the lack of per-buffered-write stream IDs prove to
>> be
>> a serious constraint in the future, somebody will certainly be motivated
>> to
>> try to find a place to store another eight bits in struct page."
>>
>> This draft patch stores stream_id in buffer head instead of page.
>
>
> This is pointless. You need to store it in the page, if the whole point is
> that you want this to be trackable. And adding it to struct page would be a
> no-go, we can't increase the size of that. See various other discussions
> around, for instance, IO priorities for buffered writeback and tracking that
> state on the side.

I googled, but didn't find related discussions.
Could you please point me a link?

Thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/